1. Field of the Invention
The present invention relates to an ink tank holder for detachably supporting an ink tank having a configuration to inform its own conditions such as an ink residual quantity used in ink jet printing by means of light emission of an indicator such as a light emitting diode (LED). The present invention also relates to an ink tank which is attachable to and detachable from the ink tank holder, and to an ink jet printing head cartridge provided with the ink tank holder.
2. Description of the Related Art
In recent years, print applications while connecting a digital camera directly to a printer as a printing apparatus without use of a personal computer (PC) are increasing along with spread of digital cameras. Moreover, print applications configured to perform data transfer by attaching a card-type information storage medium, which serves as an information storage medium detachable from a digital camera, directly to a printer are also increasing. While a method of checking an ink residual quantity inside an ink tank of a printer on a monitor of a PC is generally known, there is an increasing demand for grasping the ink residual quantity inside the ink tank without use of the PC in the case of printing without use of the PC. In other words, if a user is aware that the ink inside the ink tank is running out, the user is able to replace the ink tank with a new one before starting a printing operation, for example, and thereby to prevent substantive printing failures attributed to ink shortages in the course of printing operations.
In the prior art, a light emitting portion such as an LED has been known as means for informing a state of the ink tank to the user. In Japanese Patent Application Laid-open No. 4-275156 (1992), it is described that two LEDs are provided in an ink tank formed integral with a printing head, and are turned on, respectively, in correspondence to two stages of the remaining amount of ink. Similarly, in Japanese Patent Application Laid-open No. 2002-301829, a lamp is described, provided in an ink tank, capable of lighting in correspondence to the remaining amount of ink. Also, in this patent document, the above-mentioned lamp is provided in each of four ink tanks used in a printing apparatus.
On the other hand, in accordance with the recent requirement for the further improvement in image quality, light magenta or light cyan ink has been used in addition to the conventional four colors; i.e., black, yellow, magenta and cyan. Further, the use of a so-called particular color ink such as red or blue ink has been proposed. In such a case, the ink jet printer must be provided with 7 to 8 ink tanks. Thereupon, a mechanism is necessary for preventing the respective ink tank from being mounted to an erroneous position. In Japanese Patent Application Laid-open No. 2001-253087, a structure is disclosed wherein the mutual engagement shapes between mounting portions of a carriage and the respective ink tanks are different from each other. Thereby, it is possible to prevent the ink tank from being mounted to an erroneous position.
A location for disposing a light emitting portion such as an LED on the ink tank must be carefully determined in consideration of layouts of operating members for attaching the ink tank to a holder or a printing apparatus (printer) body and electrical contacts for transmitting electric signals for driving the light emitting portion. Therefore, the light emitting portion such as the LED, the operating members for fitting the ink tank, and the electrical contacts may restrict the layout freedom with one another. As a result, these members are not always disposed in the optimum locations.
For example, in the above-mentioned Japanese Patent Application Laid-open No. 4-275156 (1992), a structure of an ink cartridge is disclosed, wherein an LED is attached to a printed circuit board (PCB) for carrying out the electric communication with a printer body. According to such a structure, however, it is necessary to dispose the PCB to a position at which the LED is easily visible by the user. In addition thereto, it is necessary to provide an electric connecting part in the PCB for the electric communication with the printer body. Therefor, there is a problem in that the degree of arrangement freedom of each of the LED and the electric connecting part is restricted. While it is thought to provide a large-sized PCB for covering both preferable positions for the electric connecting part and the LED, the production cost rises therefor. When the structure disclosed in Japanese Patent Application Laid-open No. 4-275156 (1992) is applied to the printer capable of mounting a plurality of independent ink tanks for the respective colors, a structure for mounting the ink tanks onto the printer is limited. Accordingly, it is necessary either to minimize a substantial volume of the respective ink tank or to enlarge a size of the printer.
On the other hand, while there is the disclosure in Japanese Patent Application Laid-open No. 2002-301829 in that an ink alarming lamp for the ink tank is provided at a place easily visible by the user, a preferable structure for supplying a power or signals to the ink alarming lamp is not described. FIGS. 6 to 8 thereof suggest that the ink jet printing apparatus and the ink alarming lamp are connected to each other by conductor wires. However, the conductor wires in correspondence to the number of the ink alarming lamps are necessary, which complicates the wiring arrangement not only to cause the production cost to rise but also to deteriorate the visibility of the lamps by the conductor wires or the connection thereof. Also, in FIGS. 6 and 7 of Japanese Patent Application Laid-open No. 2002-301829, a structure is disclosed in which the ink alarming lamp is provided on an attaching lever which is a movable member operative for attaching the ink tank on the carriage. In this case, however, the arrangement of the conductor wires is further complicated to cause the production cost to rise and also the attachment/detachment of the ink tank becomes difficult.
These problems have been further significant because the position at which the display is carried out to be visible by the user is preferably limited to the location or in the vicinity of operating member for the attachment/detachment of the ink tanks, due to the minimization in size or the multifunctioning of the printer.
The display is not only visible by the user but also used for the control carried out by the printer body.
For example, as described above, a structure wherein lamps are provided in ink tanks is described in Japanese Patent Application Laid-open No. 2002-301829. Even in this case, however, when the control section of the printer body recognizes an ink tank in which an amount of ink remaining therein is insufficient, it is necessary to specify such an ink tank to be supplied with a signal for the purpose of lighting the lamp based on such the recognition. For example, when the ink tank has been mounted at an erroneous position, there might be a possibility in that another ink tank in which a sufficient amount of ink remains is displayed as no ink remains therein. Accordingly, when light-emitting control of the display such as a lamp is carried out, it is necessary as a prerequisite to identify the position of the ink tank to be mounted. To solve such problems, the light-emitting control of individual LED is carried out in each of a plurality of ink tanks, based on an output state of a light receiver section fixed in the printer, to identify the position at which the ink tank is mounted.
As described above, the LED on the ink tank may be required to have not only a function to emit light for informing the user of conditions but also a function to emit light toward a light receiver provided on the printing apparatus body for achieving desired control. From this point of view, it is undesirable to underutilize the light emitting functions due to the layout restriction of the LED.